USLegal.com defines a mistrial as “the termination of a trial before its natural conclusion because of a procedural error, statements…which prejudice a jury, a…jury [not] reaching a verdict after lengthy deliberation (a ‘hung’ jury), or the failure to complete a trial within the time set by the court.” Thus, the word, “mistrial” is exactly what it sounds like: it’s a trial that has not operated in an acceptable or orthodox manner.
When the standards of fairness to which a trial is held are compromised in some way, a mistrial is declared and the defendant(s) may be retried.
When Amanda Knox and her then boyfriend, Raffaele Sollecito were convicted of the 2007 slaying of Knox’s housemate, Meredith Kercher, both were sentenced in Italy to spend a quarter-century in prison. Knox claimed that she had been beaten by police into a false confession, and that her conviction was therefore the result of a mistrial. (The Italian court did not agree; in fact, the prosecutors contended that the media circus biased the jury in favor of Knox.) In any case, Knox has since returned to the U.S. after the conviction of another suspect, another examination of DNA evidence, and 4 years in prison, but the case remains heavily controversial. She may be retried either in absentia or again in Italy at the request of Italy’s highest court.
Other Important Information
Generally, a mistrial that has been granted at the request or with the consent of the defendant is a slate wiped clean. A retrial after a mistrial is not a violation of safeguards against double jeopardy, since the original trial has been effectively negated. However, when a judge oversteps their authority (in declaring a mistrial against the will of a defendant, or in a way that makes the defendant’s conviction more likely in a retrial, as in United States v. Jorn), a retrial may constitute double jeopardy.